Remotely controllable system for positioning on a patient an observation/intervention device

ABSTRACT

A remotely controllable system for positioning on a patient an observation and/or intervention device, including a frame to which the device is bound with a number of degrees of freedom; flexible connection means, each of which is arranged between the frame and a point attached to the patient&#39;s support or to the patient himself; remotely controlled means for modifying the length/tension of the binding means; and means for remotely observing the device behavior.

BACKGROUND OF THE INVENTION

The present invention relates to a remotely controllable system forpositioning a mobile observation and/or intervention system on apatient. It applies, for example, to medical analysis systems, such asendoscopic or echographic systems or to simple invasive devices such asa puncture needle. It will more specifically be described in the contextof the use of an echographic probe (remote echography).

Echography is a very advantageous imaging modality, because of itslightness, harmlessness, and its richness in morphological andfunctional information. Its implementation requires a particularspecialization. Several clinical situations would require for theexamination to be performed by telemedicine means.

The simplest solution, used in some telemedicine operations, is for alocal operator to put himself in vocal and possibly video connectionwith a distant expert doctor. It could then be devised for the nurse oreven for the patient himself to handle an echographic probe and for thedistant expert to guide him and draw a diagnosis therefrom. Suchresorting to a distant expert is used in several medical situations butapplies with difficulty to echography. Indeed, in echography, theperforming and interpretation of the examination are intimatelyconnected. Only the operator, who has controlled the way in which theechographic probe has been displaced on the patient's body, has all theinformation useful for the interpretation. This feature makes remoteechography operations difficult. The local operator must already berelatively well trained, and the remote expert must be able to preciselyindicate to him the probe displacements to be performed. Now, suchdisplacements imply 6 degrees of freedom (three translations and threerotations). It can be understood that the expression by the remoteexpert of the displacement orders in vocal form, and even more theirexecution by the local operator, may be difficult.

To overcome the disadvantages of the above-mentioned simple remoteechography, it would be necessary to enable the distant expert to takecontrol of the displacement of the echographic probe, for example, bycontrolling a probe assembled on a remote-controlled robot. Such systemsusing robotics are used in medicine and especially in surgery. For thispurpose, robotic architectures of master-slave type are typically used,in which a remote operator has a stress feedback system which enableshim to displace a virtual object according to n degrees of freedom andin which a slave system placed close to the patient reproduces themaster's motions while said master can feel a resistance to its motion.

In the conventional approach, the master and the slave execute exactlythe same motions, the slave being linked to a referential with respectto which the patient's position must be located. The mechanicalconstraints to which the slave is submitted must remain within limitscompatible with the possibilities of synthesis of a stress feedback bythe master. Besides, the used mechanical architectures use rigid andrelatively heavy structures, even when the useful load has a weightsmaller than 10 N. It is thus imperative to design high-performancesecurity systems, able to forbid uncontrolled motions of the robot,which would be likely to harm the patient or the medical and surgicalteam surrounding him.

FIG. 1 shows a very simplified side view of a patient 1 lying on a table3 for a conventionally remotely controlled echographic examination. Anechographic probe 5 is arranged to contact the patient, for example, hisabdomen, by an articulated and remote controlled robot arm system 7.Such a system implies a heavy computer architecture to ensure thecontrol and stress feedback. It should be noted that the slave(supporting the echographic probe) contacts the human body, which exertsagainst it variable and widely unpredictable pressures. This requires,if the system is desired to securely operate, implementing an extremelycomplex system. Due to all these constraints, the slave is a costlysystem.

The dilemma thus currently is the following: to use a local operatorguided by a distant expert, which appears to be poorly adapted, or touse a robotic system, having a particularly heavy and expensivemechanical structure and associated computer system.

More generally, the above problem, that is, to provide a low-cost secureremotely controlled positioning system, is posed in many other casesfalling or not within the medical field. In the medical field, a problemof the same type is posed, for example, for the remote control inorientation and in position of an endoscope or a puncture needle.

Operations performed under endoscopy grow in number. They requireintroduction of various tools of generally cylindrical shape through theskin. The number of these tools may be such that the operator isdisturbed by its assistants which maintain them for him in an adequateposition. For this and other reasons, various systems have beendeveloped to bear and position tools penetrating into the human bodyupon interventions under endoscopy. These systems are “conventional”robots, which are fastened to the operating table or to the ground, andwhich displace the tools that they support to the coordinates which arecommunicated thereto by various interfaces with the user, or even, insome cases, by control of the images observed by the endoscope. Suchsystems remain heavy and require specific adaptation to take intoaccount security problems linked to the use of relatively rigid systemssupporting surgical instruments.

The puncture of various organs of the human body is a widely used methodto sharpen a diagnosis (sampling of material for microscopic analyses,measurement of various physical, and especially electric characteristics. . . ), or for therapy (physical, mechanical, chemical, electricdestruction . . . ). In many cases, the puncture is performed undercontrol of imaging means (radio, echography, scanner, MRI . . . ). Itmay be advantageous to robotize the positioning of the puncture needle,which opens up the way to the automated implementation of the puncturegesture in several clinical situations, among which, in particular:

-   -   a physically limited access to the patient (scanner, MRI . . .        ),    -   the need to perform the gesture rapidly, and    -   the need to perform the gesture from a distance.        Again, existing remotely controlled robotization and positioning        systems are too heavy to enable easy generalization of this type        of application.

BRIEF SUMMARY OF THE INVENTION

Thus, an object of the present invention is to provide a remotelycontrolled system for positioning a diagnosis or therapeutic devicewhich is relatively simple.

Another object of the present invention is to provide such a systemwhich has a low cost while avoiding any risk for the patient and thepeople around him.

Another object of the present invention is to provide such a system inwhich it can be passed from a remote control to a local handling of thecontrolled device.

Another object of the present invention is to provide a specificremotely controllable device for displacing an object.

To achieve these objects, the present invention generally provides aremotely controllable system for positioning a useful load, in which:

-   -   the components exhibit compliance features, that is, are likely        to reversibly deform under the effect of moderate mechanical        constraints, external to the system (this implies in particular        that the system be not only formed of rigid arms); and    -   the motions tend to reproduce the order of a remote operator,        but taking account of the system environment, especially of the        topography of the site in which is placed the device having a        remotely controlled displacement (light control), and without it        being necessary to know at any time the geometric        characteristics of the various system components.

Such a system thus differs from conventional robots, most of thecomponents of which are rigid, and in which a compliance can only beobtained by specific characteristics of the joints between the rigidelements, and the control of which implies as fine a knowledge aspossible of the geometric characteristics of the robot, a coordinatechanger typically enabling passing from the “articular” coordinates ofthe robot to the Cartesian coordinates, by means of a model of therobot.

The “compliance” and “light control” properties are particularly welladapted to medicine applications, when diagnosis or therapeutic toolsare desired to be displaced on the human body. The compliance enableshaving the system and the tools that it bears directly contact thepatient (whose body may even be used to help supporting the system andits useful load). The light control cannot be a handicap; indeed, theprecise knowledge of the position of the system and of the controlleddevice in a referential external to the patient (provided by the“conventional” control) teaches much less than the knowledge of theposition of the useful load with respect to the anatomic or therapeutictargets of the human body. Now, this relative position information canbe provided by the controlled device itself, by various sensors, or bylearning.

More specifically, the present invention provides a remotelycontrollable system for positioning on a patient an observation and/orintervention device including a frame to which the device is bound witha number of degrees of freedom; flexible connection means, each of whichis arranged between the frame and a point attached to the patient'ssupport or to the patient himself; remotely controlled means formodifying the length/tension of the binding means; and means forremotely observing the device behavior.

According to an embodiment of the present invention, each of theflexible binding means is of cable, thread, or strap type.

According to an embodiment of the present invention, each of theflexible binding means is resilient.

According to an embodiment of the present invention, the remotelycontrolled means include winder motors.

According to an embodiment of the present invention, the remotelycontrolled means include artificial muscles.

According to an embodiment of the present invention, the connectionbetween the frame and the device is ensured by remotely controlledflexible binding means.

According to an embodiment of the present invention, the device is anechographic probe, and said remote observation means enable observationof the echographic image.

According to an embodiment of the present invention, the device is anendoscope, and the remote observation means enable observation of theendoscopic image.

According to an embodiment of the present invention, the device is aneedle holder, and the remote observation means enable observation of animage of scanner, MRI, . . . type.

According to an embodiment of the present invention, the link betweenthe patient and the distant remote-control central station includes anaudio link.

The foregoing objects, features and advantages of the present invention,will be discussed in detail in the following non-limiting description ofspecific embodiments in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a remote echography system using conventional robotictechniques;

FIG. 2 is a very simplified top view of a remote echography systemaccording to the present invention;

FIG. 3 is a partial view of an example of a supporting frame of anechographic probe usable according to the present invention; and

FIG. 4 is a partial view of another example of an echographicprobe-supporting frame usable according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will first be more specifically described in thecontext of the use of an echographic probe (remote echography).

The present invention is based on an analysis of the actual needs of aremote echography operation. The distant expert must be able to:

-   -   have a general vision of the scene, and dialog with the patient        and with the local staff,    -   control the acquisition parameters of the echograph,    -   visualize the echographic images,    -   indicate, by displacing a virtual probe, the direction of the        desired displacements of the real probe (six degrees of        freedom),    -   displace the real probe according to these indications,    -   control on the echographic images the way in which the        displacement orders are really taken into account,    -   adapt the orders to the way in which they are executed and to        needs,    -   possibly have, from the virtual probe, an information feedback        concerning the pressure exerted by the real probe on the        patient.

The patient or a local operator must also be able to:

-   -   initialize the probe displacement system,    -   interrupt the probe displacement if it becomes painful (too high        a pressure, for example),    -   give back the control to the expert after such an interruption;        and    -   possibly manually displace the probe, according to the expert's        vocal indications, to face specific situations.

The applicant has found that these requirements could be betterfulfilled with a remotely controlled system having a compliant structureand a light control than with a master-slave type robot of rigidstructure such as previously described. Further, the use of a flexibleor compliant remote displacement structure avoids forbidding any motionto the patient during an analysis, which, in the case of an echography,may be relatively long.

According to an aspect of the present invention, the applicant has notedthat, in fact, when an echography is performed, the expert has asufficient indication of the motions that the probe has performed andthat it desires it to perform from the echograhic image that hereceives. For him to know exactly the probe positioning with respect tothe patient matters little. It is enough that, from a given positioning,he can perform a displacement roughly in a desired direction(translation, rotation) and that, after each incremental displacement,he can decide whether he desires to continue the displacement in thesame direction or move in another direction to better see what isdesired to be observed. Thus, the present invention provides suppressionof any rigid connection between the probe and the patient's support.Further, the echographic probe sustentation or suspension function issuppressed. The system displaces the probe on the patient's body whilesaid probe rests on said body.

FIG. 2 shows an embodiment of the present invention. A patient 1 lyingon a table 3 is considered again. Echographic probe 5 moves along with aframe 11 laid on the patient's body. According to the present invention,various flexible mechanical means such as straps, threads, cables, orthe like are provided to have frame 11 of a probe slide on the patient'sbody around a selected location. For example, in the embodiment shown,frame 11 is attached to four straps 12, 13, 14, and 15, the second endsof which are attached at points 16, 17, 18, and 19. Points 16 to 19 mayfor example be binding points attached to table 3. They also may bebinding points attached to straps respectively arranged around thepatient's arms and thighs. It should be understood that by providing atthe level of the connection between each of the straps and the frame awinder motor, the displacement of frame 11 around an initially selectedarea and its pressure on the body can be remotely controlled. Areleasable means will preferably be provided to enable manuallypositioning frame 11 in an initial position.

As shown in FIG. 3, frame 11 may be a package in which echographic probe21 is mobile in a remotely controllable way. For example, the probe isbound to an arm 22 mobile in the package perpendicularly thereto, toapply a higher or lower pressure between the probe and the patient. Arm22 will for example be mobile in rotation around its axis (direction α)and with respect to this axis around a joint 23 (direction β).Conventionally, more or fewer degrees or freedom may be provided.

In the embodiment of FIG. 4, frame 11 is a simple plate on which isassembled, for example by a ball joint system 31, an echographic probe30. The probe body may be displaced and oriented with respect to theplate by means of an assembly of automatic actuators 33, 34, 35. Thepneumatic actuators are for example inflatable tubes currently called“artificial muscles”, the length of which decreases when they receive agas under pressure.

Although this is not described in detail herein, means for controllingthe various motors and other previously-described remotely controllablemeans with the displacements of a master unit handled by a remoteoperator communicating with the drive system just described by any meanssuch as a radio link, an optical cable link, or other, are known in theart.

Various modes of action on the controlled device may be provided.

The device displacement may be completely automated and correspond to apredetermined strategy. This strategy for example aims at fulfilling acriterion of complete scanning by the echographic probe of a selectedanatomic volume.

The displacement of the device may involve an expert who uses the imagesgenerated by the device or physical information characterizing thedevice behavior to adapt his medical strategy. The physical informationmay especially be:

-   -   position information, provided by video cameras, a        three-dimensional locator, or length encoders of the flexible        binding means,    -   physiological signals generated by the device or by sensors        coupled to the device, or    -   measurements of the pressure or of the mechanical stress exerted        by the environment on the system.

To ensure the patient's security, and avoid for excessive pressures tobe applied to him by the probe or its frame, it may be provided forstraps 12–15 to have a certain resilience, or to be bound by rupturesystems. Any other passive security system may be provided to avoid forthe slave to exert on the patient any force or pressure beyondpredetermined limits. Similarly, the elements of displacement betweenthe probe and the frame may be flexible, and possibly resilient.

The system of FIG. 2 is an example only of implementation of the presentinvention. The basic aspect of the present invention is that it providesa system enabling remote control of the sliding and orientation of atherapeutic or diagnosis device on the human body. Many alternativeembodiments may be provided to ensure this function. For example, thestraps may be replaced by any other “thread” system possibly driven by“artificial muscles” (inflatable tubes tightened in braids exertingvariable tractions under the effect of pressure variations generated byvalves likely to be controlled by computer means), or by rigid cradleand spring systems. Of course, it will further have to be provided forthe various system components in contact with the skin to slide thereon.The straps may for example, in the case of the specific describedembodiment, be soaked with an echographic gel.

It is particularly simple, for a local operator or for the patienthimself, to rapidly release the system by means of an easily accessiblecontrol to interrupt the remotely controlled displacement if the systemshould become painful, or to displace the frame as selected and requiredby the distant expert to whom the patient is linked by an audio andpreferably video link.

An application to an endoscopic system will be implemented in ananalogous manner, the information feedback between the endoscope and theremote expert corresponding to the very image provided by the endoscopiccamera.

In the context of an application such as the placing of a punctureneedle, the image feedback to the distant expert may come from one orseveral video cameras observing the general scene, from atri-dimensional locator able to follow the position or the orientationof the needle, or from a specific imaging system (X-rays, scanner, MRI .. . ).

1. A remotely controllable system for positioning on a patient anobservation and/or intervention device including: a patient's support onwhich the patient resides during a diagnosis; a frame to which thedevice is bound with a number of degrees of freedom; a plurality offlexible connection means, each of which is arranged for flexiblyconnecting the frame and a point adapted to be attached to the patient'ssupport or to the patient himself; connecting the frame to differentconnection points on the patient's support remotely controlled means formodifying the length/tension of the connection means; and means forremotely observing the device behavior, capable of controlling saidremotely controlled means.
 2. The system of claim 1, wherein each of theflexible connection means is one of a cable, a thread or a strap.
 3. Thesystem of claim 2, wherein each of the flexible connection means isresilient.
 4. The system of claim 2, wherein the remotely controlledmeans include winder motors.
 5. The system of claim 1, wherein theremotely controlled means include artificial muscles.
 6. The system ofclaim 1, wherein the connection between the frame and the device isensured by remotely controlled flexible connection means.
 7. The systemof claim 1, wherein the device is an echographic probe, and said remoteobservation means further enable observation of the echographic image.8. The system of claim 1, wherein the device is an endoscope, and theremote observation means further enable observation of the endoscopicimage.
 9. The system of claim 1, wherein the device is a needle holder,and the remote observation means enable observation of an image fromX-rays, scanners, or MRIs.
 10. The system of claim 1, wherein theremotely controlled means for modifying the length/tension of theconnection means is controlled by the patient by an audio link.
 11. Asystem for remotely controlling position of a diagnostic device on apatient, the system comprising: a patient's support on which the patientresides during a diagnosis; a frame on which the diagnostic device isattached; a plurality of flexible connection means, each of the flexibleconnection means connecting the frame to different connection points onthe patient's support; remotely controlled means for adjusting thelength and tension of each of the flexible connection means, whereinchanging the length and tension of each of the flexible connection meanschanges the position of the diagnostic device on a patient.
 12. Thesystem of claim 11, wherein adjusting the length and tension of theplurality of flexible connection means define direction of thediagnostic device as it moves from one position to another position onthe patient.
 13. The system of claim 11, wherein each of the flexibleconnection means is one of a cable, a thread or a strap.
 14. The systemof claim 11, wherein the plurality of flexible connection means consistsof four flexible connections.